Dilactones and their preparation from carbon monoxide and acetylenes



United States Patent 2,840,570 I p DILACTONES AND THEIR PREPARATION FROM CARBON MONOXIDE'AND ACETYLENES John C. Sauer, Cragmere, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application November 25, 1955 Serial No. 549,155

11 Claims. (Cl. 260-343.6)

Acetylene and Carbon Monoxide Chemistry, Reinhold Publishing Co., New York (1949), page 247].

It is an object of this invention to provide new compositions of matter and methods for their preparation. A further object is to provide new chemical intermediates and processes for preparing useful hydrogenated products therefrom. A still further object isto provide new dilactones and methods for their preparation. Another object is to provide novel catalytic processes for preparing useful products from acetylenes and carbon monoxide. v Still another object is to provide a new method for preparing suberic acids. Other objects will appear hereinafter.

These and other objects of this invention are 'accomplished by providing new dilactones corresponding to C (RR') O wherein R and R' are hydrogen, haloaryl, alkoxyaryl or hydro-carbon radicals free from non-aromatic unsaturatio-n and methods for theirpreparation. This invention specifically provides new unsaturated dilactones corresponding to C H O characterized in having specific absorptive coefiicients in the neighborhood of 3300 to 3400 A. of 200 to 224, melting from 220 to 250 C., having a hydrogen number, determined .with palladium-on-charcoal corresponding to about 3 moles of hydrogen per molecule, and yielding 'suberic acid on hydrogenation with platinum in acetic acid or other polar solvents. There is also provided a method for preparing suberic acids from acetylenes and carbon monoxide through the dilactones of this invention as intermediates. This invention further provides a method'for obtaining hexahydrodilactones by saturation of the carbomcarbon unsaturation of said dilactones.

It has now been found that if an acetylene and carbon monoxide are reacted in an inert organic solvent in con-'- tact with a cobalt carbonyl catalyst, there are obtained new dilactones corresponding in composition to C (RR') O in which R and'R' have the previously indicated meanings. These dilactones show strong absorption lines in the ultraviolet spectra in the region of 3300 to 4400 A. and in this region have specific absorption coeflicients of 75 to 224. They also yield suberic acids on hydrogenation with platinum in acetic acid. I

The dilactones of this invention correspond to the formula C (RR') O and exist in isomeric forms. These include a cis and a trans form wherein R and R are hydrogen, alkoxyaryl, especially Where the alkoxy radical is not more than 12 carbon atoms and the aryl'radical H is hydrocarbon of not more than 10 carbon atoms,;haloaryl, especially chloroaryl where the aryl radical is hydro-L carbono'f not more than 10 carbon atoms, or monovalent hydrocarbon radicals free from non-aromatic unsaturation, especially of not more than 12 carbon atoms, "e. g., alkyl, especially short chain alkyl, i. e., containing less than 7 carbon atoms, aryl, especially where the aryl radical is hydrocarbon of not more than 10 carbon'atoms, aralkyl, especially of not more than 7 carbons, or cycloalkyl, particularly of not more than 7 carbon atoms.

Examples of such radicals are methyl, ethyl, octyl, decyl, dodecyl, phenyl, tolyl, xylyl, benzyl, cyclohexyl, naph thyl, methylcyclohexyl, methoxyphenyl, ethoxyphenyl,

decyloxyphenyl, dodecyloxyphenyl, dodecyloxynaphthyl,

chlorophenyl, chloronaphthyl, and the like.

The dilactone from acetylene and carbon monoxide corresponds in molecular formula to C H O Two structural isomeric forms have been isolated and identi-' lied and correspond to the trans and cis forms of [A -bifuran]-5,5'-dione, as follows:

and

' Trans form (Higher melting isomer) Cis form The lower melting isomer which is the principal product of the reaction, as'carried out in Example I, below, has a melting point of 230-237 C. and the higher melting isomer has a melting point ,of 240-248 C., determined in a capillary tube in an electrically heated melting point apparatus. peatedly from methyl ethyl ketone to give samples melting at 235 and 247 C., respectively, when a setting is used. such that the temperature increases from 175 to 200 C. in 6 minutes, from 200 to 225 C. in9 minutes,

and from 225 to 247 C. in 11 minutes- The melting is generally accompanied by sublimation and decomposition. I j

The two isomers are further distinguished by their ultraviolet absorption: The pure lower melting isomer hasits maximum absorption at about 3400 A. and its specific absorbence, k is 200-204. The pure higher. I

melting isomer has its maximum absorption at about 3340 A. and its specific absorbence k m A, is 220-224. Thus the ultraviolet specific absorbence for the C H O compound is from 200 to 224.

f" isomer rests primarily on the infrared absorption peaks at 6.0a and 6.5 1. (doublet) in the conjugated unsatura-' astride a center of symmetry and will not absorb. The

tion region. The intense band at 6.0 which is virtually absent for the low melting isomer, is due to the bridge double bond. On the trans structure, this double bond is cis structure has no center of symmetry and the central double bond will absorb. The doublet at 6.5g in the spectra of the high melting form is due to the ethylenic.

double bond of each ring. The low melting form shows only a single peak at 6.5 and this is consistent with a trans structure having a center of symmetry.

FatentedJune 24, 1958 The'isomers can be recrystallized're- 3 The low melting isomer can be isomerized to the high melting or cis form by treating it with sulfuric or phosphoric acid or pyridine. The cis isomer can also be obtained from the trans isomer by recrystallization of the trans isomer from dirnethylformamide. -It can also be produced directly from carbon monoxide and acetylene wherein R and R are defined as aforesaid. These unsaturated dilactones can 'be represented by the general. formulas and wherein one free valence of each ring is satisfied by R and the other free valences of said rings are satisfied by R, said R and R being defined as aforesaid.

The new dilactones of'this invention are obtained by reacting an acetylene with carbon monoxide in an inert organic solvent in the presence of a cobalt carbonyl catalyst. In one method of operation, a pressure reactor is charged with an inert organic solvent, i. e., one free from active hydrogen, and a catalytic amount of a cobalt carbonyl catalyst, the reactor is closed, cooled to C., or lower, and evacuated. A predetermined amount of acetylene is then admitted from a storage vessel calibrated so that the amount of acetylene delivered is measured by the drop in pressure, and the reactor placed in a shaking device. Carbon monoxide is introduced to between 50 and 3000 atmospheres, usually 250 to 1000 atmospheres, and the charge heated and agitated at 60 to 175 C., usually 85 to 140 C. These conditions are maintained until there is no further reaction, as evidenced by cessation of pressure drop. Throughout the reaction period the pressure within the reactor is maintained Within the limits selected for operation by periodic injections of carbon monoxide.

After reaction is complete the reactor is permitted to cool, unreacted acetylene and carbon monoxide are vented to the atmosphere, and the reaction mixture sl-urried with an inert organic solvent. The slurry is filtered and the residue on the filter extracted with a hot inert organic solvent. The extract is cooled and the crystalline product, which separates is filtered and dried.

An alternative method for isolating the desired dilactone is by heating the crude reaction product at 200 C. and 1-2 mm. pressure, and collecting the sublimate on a cold finger. 1

The unsaturated dilactones of the aforesaid formula C (RR') O of this invention can be hydrogenated in dioxane with a palladium catalyst to the corresponding hexahydrodilactones. Thus when either the trans or cis isomer of [A -bifuran]-5,5dione is hydrogenated in solution in an organic solvent over a palladium pressure varying from 700-900 atmospheres.

catalyst, there is obtained the hexahydrodilactone, tetrahydro-[2,2-bifuran]-5,5-(2H,2H)-dione, represented by the structural formula Hg CH3 H10 CH2 7 The reduction of the unsaturated dilactone to the hexahydrodilactone is preferably realized with palladium at temperatures of 20 to 150 C. and pressures of 10 to 2000 lb./sq. in. The amount of catalyst used ranges from 1 to 20% by weight of the unsaturated dilactone.

Any palladium catalyst may be used. Thus, there may be used palladium or any of its compounds such as the oxide, chloride, nitrate, etc., and the catalyst may be unsupported or supported on inert 'base materials. Compounds of palladium appear to be more or less completely reduced to palladium metal during use. Suitable supports are charcoal, alumina, calcium carbonate, pumice, silica, etc. The particle size of the support may vary from 40 to 300 mesh for use in fluidized systems, Whereas for use in fixed bed systems supports of larger particle size, e. g. 4 to 40 mesh are satisfactory.

A suitable palladium catalyst is prepared by depositing palladium chloride on granular activated coconut charcoal, in amount sufficient to give a concentration of 0.2 to 20 g. of palladium per liter of catalyst. Preferably the charcoal is subjected to pre-treatment with an acid such as nitric acid prior to contacting it with the palladium compound. A typical preparation is the following.

A solution of 8.33 g. of palladium chloride in 5.5 ml. of concentrated hydrochloric acid and 40 ml. of water is prepared by heating the mixture on a steam bath. The resulting solution is poured into a solution of 135 g. of sodium acetate trihydrate in 500 ml. of water contained in a one-liter reduction bottle. Forty-five grams of activated coconut charcoal is added and the mixture is hydrogenated until hydrogen absorption cases, which is between 1 and 2 hours. The catalyst is collected on a suction filter and washed with 2 liters of water in five portions. The filter cake, after removal of most of the water, is dried in air and stored in a desiccator over calcium chloride. The catalyst, which weighs from 40 to 50 g. and contains about 10% palladium, is stored, after being powdered, in a tightly closed container.

The examples which follow are submitted to illustrate and not to limit this invention.

EXAMPLE I Preparation of the dilactone C l-1,0 from acetylene A 400-ml. stainless steel shaker tube was flushed with nitrogen and charged with ml. of acetonitrile containing 1 g. of cobalt carbonyl. The tube was closed, cooled in solid carbon dioxide/methanol, and nitrogen was removed by evacuation. By means of 'a caEibrate-d reservoir, 26 g. of acetylene, previously passed through two towers containing activated alumina and sodium hydroxide, was added to the shaker tube. The shaker tube was placed in an electrically heated box which was shaken vigorously. Carbon monoxide was introduced into the shaker tube, as the tube warmed up, and the actual reaction was carried out at C. during 15 hours at a Carbon monoxide was added periodically as required to maintain this pressure. The carbon monoxide absorption was of brick red crystals, melting at 220 C. and analyzing:

Analysis.-Calcd. for C H O C, 58.50%; H, 2,50%; M. W., 164. Found: C, 58.65%, 58.67%; H, 2.47%, 2.62%;M. W., 170, 172; N, trace.

After recrystallization from ethyl acetate, the product analyzed: 0, 57.98%, 58.13%; H, 2.68%, 2.66%; N. E. (by titration with sodium ethanolamine in "ethylenediamine) 157.99; ultraviolet absorption maximum, max., in acetonitrile, 3400 A. The compound showed strong absorption in the infrared at 5.6511 for lactone carbonyl unsaturation and a single very strong band at 6.50 1 due to C=C unsaturation. These infrared data and the analysis fit the structure of the dilactone [A bifuran] -5 ,5 '-dione.

EXAMPLE II Part A.Preparati0n of the dilactone C H O from acetylene A shaker tube ,was charged with 100 m1. of acetone containing 2 g. of cobalt carbonyl and 1 g. of pyridine.

Twenty-six grams of acetylene was metered into the tube and the reaction was carried out at 110 C. for 15.5

hours at 820-900 atmospheres of carbon monoxide pres-- and 25-40 mm. and yielded 0.5 g. of an orange-red crystalline residue which melted at about 214 C.

The ether-insoluble solid reaction product was extracted with warm acetone, yielding 9.5 g. of orange colored crystals. Analytical data on this material was as follows: Found-C, 59.38%, 59.83%; H, 2.69%, 2.82%, The compound was soluble inaqueous alkali. The infrared absorption spectrum of this compound was the same as that of the product of Example I, except for slight intensity variations, indicating that this compound was the same dilactone as the material obtained in Example I. e

Analytical data on recrystallized or sublimed samples of this product are given in Table I:

40 minutes. The reaction mixture was separated from the catalyst and the acetic acid removed under vacuum. The solid remaining in the flask was recrystallized from water, M. P. 127-130" C. Infrared analysis indicated almost pure suberic acid with a faint impure band at the A T he hydrogen absorbed in the reaction lactone position. was beyond that needed for saturation of carbonzcarbon double bonds as required for hydrogenolysis of thelactone linkages.

The suberic acid prepared as above was converted to the p-toluidlde, melting point 2l0-212 C. p A recrystallization from acetone did not raise the'melting point to the reported 218 C. value of the p-toluidide. However,

a mixed melting point with an authentic sample of the p-toluidide of suberic acid showed no depression.

Part C.Hydrogenati0n of the dilactone C l-I 0 tothe saturated dilactone, C H Q,

Hydrogenation of the dilactone C H O prepared as,

described above, in dioxane with palladium catalyst at C.- resulted in-the absorption'of 3.38 moles of hydrogen. and the product was a viscous oil'which distilled mainly at' 195-206" C./4 mm. The material upon standing deposited crystals. A sample which was recrystallized from an ether/petroleum ether mixture melted at 99-100 C. This product reacted with 2 moles of alkali indicating a dilactone structure.

Analysis.Calcd for C H O C, 56.40; H, 5.90; sap.

No., 662. Found: C, 56.41; H, 6.15; sap. N0., 669, 649.

' Infrared analysis of the hexahydrodilactone, tetrahydro- [2,2'-bifuran]-5,5-(2H,2'H)-dione indicated a strong ab sorption for carbonyl group in a lactone and the absence of hydroxyl groups or carbonrcarbon double bonds. Saponification number corresponded closely to the theory for reaction with two moles of alkali and the quantitative hydroxyl number was virtually zero. 1.7-"g. sample of the hexahydrodilactone and 0.8 g. of anhydrous hydrazine were warmed on a steam bath. After 15 minutes to one hour the mixture had completely solidified at steam bath temperature. After :two hours, the mixture was cooled and recrystallized from water. The resulting dihydrazide analyzed as follows:

Analysi. t.-Calcd. for' C H O N C, 41.10%;YH, 7.70%; N, 23.80%. 23.38%, 23.34%. V

The S benzylisothiourea derivative was prepared by adding 4 g. of S-benzylisothiourea hydrochloride to 1.7 g. of the disodium salt formed by saponification of the hexa- Type of Analyses Theory Found C; H (recryst. sample) C, 58.5%;11', 2.5%

M01. Wt. (reeryst. sam 1e) 164 C; H (sublimed sample O, 58.5%; H, 2.5%.-. C, 58.45%; H, 2.81%. M01. Wt. (sublimed sample) 164 155, 162. 7 Neutral equiv. (by titration with sodium 164 160.71.

ethanolamine in ethylenediamiue). Sap. Equlv. (for 3 M) 54.7-. 60.8, 59.6. Hydrogenation (Pt/HOAc), g. Hg per g. .0615 .0517. .0516.

.sample (for 5.0 M). Hydrogenation (Pd/dioxane), g. Hz per g. 0.0368 .0412.

sample (for 3.0 M). Ultraviolet absorption maximum A max., 3,360 A.

in acetonitrile.

Part B.Hydr0genation.0f the dilactone C H O to suberic acid drodilactone with sodium hydroxide, i .e., the compound 7 H n N300C-CHfl CH2 J -CH2 CH2 OOONB. I 7 0H 0H V in water and concentrating the mixture by distillation at room temperature under 20 mm. pressure. The crystals which separated from the mother liquor were-collected and recrystallized from a water/dioxane mixture This .sorption was very low and slow during the next hour and product melted at 97-l05 C.

Found: C, 41.26%; H, 8.02%.; N,

7 Analysis of the S-benzylisothiourea derivative. Calcd. fGI' C24H34O6S2N41 C, H, N, Found: C, 53.63%; H, 5.75%; N, 10.24%, 10.56%.

EXAMPLE III Preparation. of the dilactone C H O with acetylene in various recreation media Table II, below, summarizes a series of runs A, B, C and D, carried out as described in Example I, using the indicated conditions and the reaction media listed in place of acetonitrile.

EXAMPLE v1 Preparation of the dilactone C H O from hexyne-3 Following the procedure of Example I, using a charge TABLE II -Rim A B C D g. of 01H; 26 26 26 26.- g. Cobalt Carbonyl. Q 1 1.5. Reaction Medium (ml.) Ethyl acetate n-Butyl acetate Xylene (206).- Methylpyrrol- 100 (100). idone (125).

T C 90-100 95-103 102-113 90-11. 00 Pressure, Atmospheres 650-920 790-990 700-855 750-950 Time, Hours 15.5-.. 3.0.. 15.7..- 15.7. Yield, gins-.. 19--. 31 20 50. Yield, Percent 12 19 12 31.

EXAMPLE IV consisting of 100 ml. of acetone, 2 g. of cobalt carbonyl,

Preparation of the dilactone C H O. fr pheWyL 40 g. of hexyne 3, and operating at 110 134 C. under acetylene In accordance with the procedure described in Example I, a pressure reactor was charged with 100 ml. of acetone, 1.5 g. of cobalt carbonyl, and 80 g. of phenylacetylene. The charge was heated at 9l-110 C. for 15.5 hours under a carbon monoxide pressure of 770-965 atmospheres. The reaction mixture was filtered and the product on the filter separated and recrystallized twice from xylene. There was obtained 22 g. of a crystalline dilactone melting at 146-175" C. From the filtrate and mother liquor there was obtained an additional 3.5 g., making a total of 25.5 g. of the dilactone, [A -biphenylfuran)]5,5-dione. The molecular weight value obtained for this dilactone was 325, as compared with the theoretical value of 316 for C T-1 0 This dilactone showed a maximum absorption in the ultraviolet at 3820 A. and the specific absorptivity coeflicient sazo A.=118- Analysis.-Calcd for C H O C, 75.9; H, 3.8; mol. wt., 316. Found: C, 76.3; H, 3.9; mol. wt., 325.

EXAMPLE V Part A.-Preparati0n of the dilactone C H O from n-butylacetylene The above example was repeated using 100 ml. of acetone, 2 g. of cobalt carbonyl, and 82 g. of n-butylacetylene instead of phenylacetylene, The reaction was conducted for 18 hours at 95-120 C. and under a carbon monoxide pressure of 700-940 atmospheres. The crude reaction mixture was discharged and distilled. The product from the fraction distilling at 190-205 C./2 mm. crystallized upon standing. A portion of this distillate was recrystallized from petroleum ether containing a small amount of ethyl acetate. After two recrystallizations the cream-colored dilactone, [A -bi(nbutylfuran)]-5,5'-dione, had a block melting point of 124 C.

Analysis.-Calcd. for'C H O C, 69.50%; H, 7.30%; M. W., 276. Found: C, 69.20%; H, 7.36%; M. W. 270.

The ultraviolet absorption spectrum showed a strong peak at 3475 A. and a weak peak at 2600 A. The specific absorptivity, k =144.

Part B.--Hydr0genati0n of the dilactone C I-1 0 to a suberic acid Hydrogenation. of this dilactone C16H2004 in acetic acid with platinum catalyst gave a hydrogen number 800-910 atmospheres carbon monoxide pressure for 16 hours, there was obtained 4.2 g. of a dilactone, which, after recrystallization from an ethyl acetate/petroleum ether mixture, melting at -96' C. The ultraviolet absorption spectra of the dilactone, [A -bi(diethylfuran)]-5,5'-dione, showed a maximum at 3440 A. and the specific absorptivity coefficient [c A.=l39.

Analysis.Calcd. for C A-1 0 C, 69.60%; H, 7.30%; mol. wt., 276. Found: C, 69.50%; H, 7.40%; mol. wt., 265.

EXAMPLE VII Preparation ofthe dilactone C l-I 0 from acetylene with cobalt acetylacetonate catalyst Following the procedure of Example I, a pressure reactor was charged with ml. of acetone, 3 g. of cobalt acetylacetonate, and 26 g. of acetylene. The charge was heated to C. under 850-1000 atmospheres of carbon monoxide pressure. These, conditions were maintained for 14 hours. The reaction mixture was discharged from the reactor and filtered. The product on the filter was collected, dried, 'andthen sublimed. There was obtained 7 g. of sublimate which by infrared corresponded to the dilactone of Example I. The infrared spectrum of this product was the same as that of Example I, except that there was a slight intensity change in the region of 598 where the shoulder disappeared and in the region of 10.75 where it increased from very weak to weak. There was also a shoulder in the region of 12.30 These minor changes in t-he infrared spectrum may be attributed to crystallineor isomeric changes or to traces of impurities, such as solvent.

EXAMPLE VIII Part A.-Following the procedure of Example 1, the reactor was charged with 100 ml. of acetone, and 2 g. of cobalt carbonyl, followed by 26 g. of acetylene. The reaction was carried out at 97-110 C. for 16 hours at a carbon monoxide pressure of 740-950 atmospheres. There was obtained, by sublimation, 32 g. of the dilactone product of Example I, .and 16 g. of a non-sublimable residue. Based on the acetylene charged, this represents a 37% conversion.

Part B.-The above procedure was repeated using 1.5 g. of cobalt carbonyl, 100ml. of acetone, 9 g. of acetylene, and carbon monoxide sufficient to raise the cold pressure to 400 atmospheres.

The reaction was conducted at 107 -1 12 C. for 4.25 hours at a carbon Comparison of this result with'that in the first partof this example shows that a low ratioof acetylene/carbon monoxide is more favorable to the formation of dilactone.

EXAMPLE IX The conversion of the acetylene to dilactone l 7 V The" reaction was then carried out at 90-93313. and 875-1000 atmospheres for .16 hours.

1 weighed 11.7 g. and was the pure dilactone,.k =204.

Preparation of the dilactone C H O from acetylene" showing efiect of low ratio of acetylene/ carbon manoxide on yield at lower total pressures Part A.-Following the procedure described in Example I, a mixture of 100 ml. of acetone and 4 g. of cobalt carbonyl was charged into a pressure reactor. Thereafter 26 g. of acetylene was metered in by the procedure described in Example I. The reaction was carried out for 15.2 hours at 110-113 C., while maintaining a carbon monoxide pressure of 250-300 atmospheres. The reaction mixture was filtered and the product on the filter collected and dried. Upon sublimation, there was obtained 7 g. of the dilactone which by infrared was found to correspond to the product of Examples I and II. The conversion to dilactone was 8.5% based on the acetylene charged into the reactor.

Part B.Following the procedure described in Example I, the reactor was charged with 100 ml. of acetone and 1.5 g. of cobalt carbonyl, followed by addition of 7.5 g. of acetylene and carbon monoxide sufiicient to raise the cold pressure to 100 atmospheres. The charge was heated at 90-116 C. under a carbon monoxide pressure of 265-300 atmospheres for 16 hours. 'The crude product, after removal of acetone, weighed 15 g. y

and contained 44% of the dilactone of Examples I and II and 19% of insoluble by-product. This corresponds to a 28% conversion, based on the acetylene charged to the reactor.

Comparison of this yield with that of part A illustrates the advantage of using a low ratio of acetylene/carbon monoxide. That this practice is especially advan- I tageous at lower total pressures is seen by comparison of this example with Example VIH.

EXAMPLE X Preparation of the dilactone C H O showing efiect of high ratio of solvent/acetylene on yield The above procedure of Example IX, part B, was repeated varying the solvent/acetylene ratio in runs (b) and (c) by increasing the volume of solvent charged while keeping the weight of acetyleneconstant, as shown in Table III. These results show that increasing the solvent/acetylene ratio is advantageous yield of desired dilactone.

EXAMPLE XI Preparation of the dilactone C H O from acetylene in cyclohexanone solvent A 400 ml. shaker tube was charged with 300 ml. of cyclohexanone and 1.5 g. of cobalt carbonyl, followed by addition of 7.5 g. of acetylene and carbon monoxide in improving the 97102 C. and 9l0950 atrnospheres of carbon mon- The cyclohexanone filtrate was recharged to the tube,

7.5 g. of acetylene was addecLand a second reaction was then run under the same conditions as the first.

each case the product collected by filtration was 100% dilactone. .Samples that were analyzed showed no de-- tectable cobalt content (hence less than 0.001% CO).. By contrast, products filtered from reactions carried out in acetonitrile contain 5-1()% of insoluble by-products; and 12% of cobalt.

EXAMPLE XII Preparation of the dilactone 0 1-1 0 from p naphthylacetylene The procedure of Example I was repeated, employing 1 mol. wt., 416. Found: C, 81.07%; H, 4.16%; mol. Wt.

The infrared spectrum showed strong absorption at' 5.65 forlactone carbonyl, and 6.15,a, 6.25 1, 6.35 4, and

6.4 for conjugated C=C unsaturation.

In addition, there was obtained 9 g. of crude dilactone.

EXAMPLE XIII Preparationof the dilactone C I-1 0,6 from pchlorophenylacety'lene The procedure of Example I was repeated with a charge consisting of 1 g.'of cobalt carbonyl, 125 ml. of acetone, and 15 g. of p-chl-orophenylacetylene, and operating at oxide pressure for 16.5 hours. There was obtained 12 g. of a product melting at 243-258 C. and showing the characteristic infrared lactone spectrum.

Analysis.-Calcd. for C H bO Cl C, 62.3%; H, 2.6%; Cl, 18.4%; M. W., 385. Found: C, 63.9%; H, 3.2%;Cl, 16.9%; M. W., 380. a

The ultraviolet spectrum showed specific. absorbence. V k =98. The product, [A bi(p chlorophenylfuran)]-5,5-dione, showed infrared, absorption at 5.65u for. lactone carbonyl, 6.25 610p, 6.73;; for C=C unsaturation, and 9.15; and 9.89 1. for-p-chlorophenylr 7 EXAMPLE XIV Preparation 'of the phenylacetylene The procedure of Example I was repeated'with. a" charge consisting of 1 g. of cobalt carbonyl, 100 ml. of

acetone, and 12 g. of o-methoxyphenylacetylene and operating at 100 C. and 900-990 atmospheres of carbon, monoxide pressure for 16.2 hours. There was obtained 18 g. of a product melting at 186 220 C. and whose infrared spectrum showed the presence of a-lactone ring, A

o-substituted aromatic ring, and the methoxyl group. The

product [N (5315) bi(o methoxyphenylfuran) ]-5 ,5 j

dione, showed specific absorbencekgm =82.,

Analysis.'-'Calcd. for. 0 mm,; C, 70.3; H, 4.3; i

sufiicient to raise the cold pressure to400 atmospheres. M. W., 276. Found: C, 70.1; H, 4.3; M. W., 391,

The product 'was filtered and the. solid was washed with ether and dried. It I The product was filtered off and, the filtrate was-recharged to the tube as before, while the solid was washed with. ether and dried. The conversions to dilactone in six successive runs made in this way were 49, 55, 63, 55, 52 and 50% of the. theoretical, based on the acetylene. In;

dilactone C H O from o-methoxy- The compound showed strong absorption in the infrared at 5.7 4. for lactone carbonyl, at 6-O5/.L, 6.25,, 6'.45,u, and 6.7 for C=C unsaturation, 8.0 4 for ether C.OC, and 13.25,u for o-substituted aromatic ring.

Methods for producing the higher melting isomer, the cis isomer of EA -bifuran]-5,5-dione are illustrated in the following examples. 7

EXAMPLE XV One gram of the dilactone of Example I was heated with 15 ml. of 85% phosphoric acid on the steam bath for several hours. The cooled solution was filtered to give 0.6 g. of a solid product, the cis isomer of [A -bifuran]-5,5'-dione, which was recrystallized from methyl ether ketone, M. P. 248 C.; [c =224.

EXAMPLE XVI A solution of the dilactone of Example I (4.4 g.) in pyridine (125 ml.) was refluxed for five hours. The solution became black, the precipitate which formed was separated by filtration, and the filtrate concentrated. There was thus obtained 1.0 g. of the cis isomer of [A -bifuran]-5,5-dione, which was recrystallized twice from methyl ethyl ketone, M. P. 243-245 C.; 3340 A.=224- EXAMPLE XVII A 19 g. sample of the dilactone of Example I was heated with 85% phosphoric acid (300 ml.) on the steam bath for several hours. The undissolved material (5.8 g.) was collected by filtration. The cooled filtrate yielded 4.8 g. of crystals. Each of these solids Was recrystallized repeatedly from methyl ethyl ketone. Various crystallization fractions melted from 246-248" C. and were each shown ,by composition and ultraviolet and infrared absorption analysis to be the isomer (total conversion 56%). The purest fraction had a M. P. of 248 C.; k =221. Thiscompound showed a strong absorption band at 6.0;. and a doublet at 6.5 and had a lactone carbonyl band at 563 Analysis: Found, C, 58.71%, 58.87%; H, 2.60%, 2.66%. On the basis of the infrared analysis this is characterized as the cis isomer of [A bifuran]-5,5-dione.

The remainder of the phosphoric acid solution .was poured into ethanol to precipitate 4.3 g. of a mixture of the two isomers of the unsaturated dilactone, which was recrystallized from methyl ethyl ketone and then characterized by melting point, composition, and spectra, M. P.

EXAMPLE XVIII The action of a three-fold excess of p-nitroaniline (10.8 g., 0.078 mole) and boiling acetic acid (350 ml.)

on the dilactone of Example I (4.1 g., 0.025 mole) for 8 EXAMPLE XIX When a solution of 2.3 g. of the dilactone of Example I in 5 ml. of concentrated sulfuric acid was allowed to stand at room temperature for several weeks, colorless crystals came out of solution. These were recrystallized several times from methyl ethyl ketone and shown by melting point, infraredand ultraviolet absorption analyses to be identical to the cis isomer product of Example XVII. The purest traction had a M. P. of 247-248" C.; k =221; C, 58.65%, 58.66%; H, 2.6 8%, 2.60%.

12 v This: cisisom'er compound shows "the same infrared absor'ption spectrum as the product of Example EXAMPLE XX A 210g. sample of the dilactone of Example I and 500 ml. of concentrated 'sulfuric'acid were heated on the steam bath for 4 hours. The cooled solution was poured into a mixture of 500 g. of ice and 2 liters of water cooled externally by an ice bath. The precipitate was collected by filtration on a sintered glass filter and recrystallized from cyclohexanone to. give 176 g. (84%) of a product which by the ultraviolet absorption analysis corresponded to the compound of Example XVII. After recrystallization from methyl ethyl ketone the cis isomer product had a [(3350 i EXAMPLE XXI A 10 g. sample of the. crude dilactone of Example I was added to 35 ml. of sulfuric acid in 35 ml. of Water. The mixture was heated for 30 hours on the steam bath. The solid material weighed 6.3 g. and was shown by u1traviolet absorption analysis to be identical to the cis isomer product of Example XVI; 10 =220, after recrystallization from methyl ethyl ketone.

EXAMPLE XXII To a'mixture of'lO g. of the crude dilactone of Example I and 15 ml; of water was added 45 ml. of concentrated sulfuric acid. Much heat was evolved and a homogenous solution-resulted. 'After several hours of gentle warming on the steam bath the solution was allowed to cool; giving crystals of the cis isomer (2.7 g.). The filtrate was poured into ice water to precipitate another 2.6 'g. of a product which by ultraviolet absorption analysis was identical to the cis isomer product of Example XVI. The main fraction when recrystallized from methyl ethyl ketone had [c =223.

EXAMPLE XXIII The crude dilactone of Example I was recrystallized twice from dimethylformamide. This recrystallized product melted at 230-245" C. and had a [c =213, which corresponds, to the values for the high-melting cis form of '[A bifuran] -5,Sfldione.

When the crude product of Example I Was recrystallized from acetone it melted at 222-224 C. which low melting point corresponds to that of the trans form of [A -bifuran]-5,5?-dione.

EXAMPLE XXIV Preparation of the cis isomer of the dilactone C H O from acetylene. in thepresence of hydrogen sulfide A stainless steel-lined pressure reactor was charged with 1.5 g. of cobalt carbonyl and g. of acetone. The reactor was then closed, chilled, and evacuated. It was further charged with 20 g. of hydrogen sulfide and 26 g. of acetylene. After heating at 98-112" C. under carbon monoxide pressure of 780-960 atmospheres for 17 hours the reactor was opened and the product discharged. It was a darkliquid with a small amount of black powdered solid. The entire product was transferred to a Soxhlet extractor and extracted with acetone for 24 hours. The extract contained no solid material but upon concentration, 0.3 g. of solid crystallized. This solid consistedof thin rectangular platelets rather than needles. Upon recrystallization from ethyl acetate this cis isomer product melted at 245 (3., about 10 degrees higher than the trans form of [A -bifuran]-5,5-dione. Further concentration of the filtrate gave 0.2 g. more of the crystalline solid cis isomer. This product contained 58.17% C and 2.75% H, as compared with calculated values of 58.5% C and.2.44%i H forc Hi O '13 EXAMPLE XXV Part A.-Preparatin of the cis isomer of the dilactone C H O from acetylene i7: presence of hydrogen sulfide Example XXIV was repeated, except that the reaction temperature was 100-104 C., the carbon monoxide pressure 825-l,000 atmospheres and the time 16.5 hours. The crystalline solid which formed was recovered as described in Example XXIV. The product melted at 241- 243 C. The ultraviolet absorption of this solid had a maximum at 3340 A., corresponding to the cis form of [A -bifuran]-5,5-dione and dilfering from the dilactone of Example I, which has a maximum at about 3400 A. About 4.7 g. of this solid was isolated. The product showed a strong absorption at 5.65 t and at 6.2,u and 625g. 7

The above cis form of the dilactone can beconverted to the hexahydro derivative by hydrogenation as described below:

Part B.-Preparati0n of the saturated dilactone, C H O from the cis isomer of the dilactone C l-I 0 A slurry of 11.0 g. of the above cis form of the dilactone in 350 ml. of acetic acid was shaken with 1.5 g. of a 10% palladium-on-charcoal catalyst and hydrogen (re-pressured to 44 1b./sq. in.) at room temperature. The hydrogenation was completed in 40 minutes. The filtered solution was concentrated under reduced pressure until white crystals appeared. The first two crops weighed 5.2 g., M. P. 104-106 C., after recrystallization from chloroform-petroleum ether. Both the crystalline and non-crystallized portions were shown by infrared data to be identical with those obtained from hydrogenation of the ordinary trans isomer of [A -bifuran]-5,5- dione.

In the formation of the dilactones of this invention, there are actually involved 2 moles of an acetylene and 4 moles of carbon monoxide. In practice, this ratio is attained by charging a weighed sample of the acetylene into the reactor and then injecting carbon monoxide in amount sufiicient to provide 2 moles thereof per mole of acetylene. Employing a 400 ml. reactor and 25-30 g. of acetylene, the amount of carbon monoxide injected is that which will provide a total pressure in the range of 50-3000 atmospheres at reaction temperature.

The reaction is conducted until there is nofurther pressure drop and this generally requires from l-20 hours, although shorter or longer reaction times can be employed. Througout the reaction period the pressur'ewithin the reactor is maintained by periodic injections of carbon monoxide.

The acetylenes used in preparing the dilactones of this invention correspond to R-CECR, wherein R and R are hydrogen, alkoxyaryl, especially where the alkoxy radical is not more than 12 carbon atoms and the aryl radical is hydrocarbon of not more than carbon atoms, haloaryl, especially chloroaryl where the aryl radical is hydrocarbon of not more than 10 carbon atoms, or monovalent hydrocarbon radicals which are free from nonaromatic unsaturation, especially of not more than 12 carbon atoms, e. g., alkyl, especially short chain alkyl, i. e., containing less than seven carbon atoms, aryl, especially where the aryl radical is hydrocarbon of not more than 10 carbon atoms, aralkyl, especially of not more than seven carbons, or cycloalkyl, particularly of not more than seven carbon atoms. Examples of such radicals are methyl, ethyl, octyl, decyl, dodecyl, phenyl, tolyl, xlyl,

naphthyl, benzyl, cyclohexyl, methylcyclohexyl, chlorophenyl, chloronaphthyl, methoxyphenyl, ethoxyphenyl, decyloxyphenyl, dodecyloxyphenyl, dodecyloxynaphthyl,

and the like. Examples of such acetylenes are acetylene, methylacetylene, Z-decyne, phenylacetylene, naphthy1+ acetylene, p-chlorophenylacetylene, p-ethoxyphenylacetylene, p-decyloxyphenylacetylene, benzylacetylene; cycloj-a hexylacetylene, methylcyclohexylacetylene, etc. r

The reaction between the acetylene and carbon monoxliquids which contain no active hydrogen, as defined by .S. Siggia, fQuantitative Organic Analysis Via Functional Groups, Znded. (1954), page 78, and' determined by the Zerewitinofi method [Ber. 40, 2026 (1907); I. Am. Chem. Soc. 49, 3181 (1927)]. Thus, the acetylene is the only compound in the reaction system which may contain active hydrogen. Specific inert organic liquids are isooc'tane, toluene, acetonitrile, acetone, ethyl acetate, dioxane, diethyl ether, xylene, benzene, etc. The nitriles and ketones are in general preferred over the hydrocarbons and ethers. V

The amount of solvent used can be varied over wide limits but generally it is at least equal to the weight of the acetylene charged into the reactor. An amount in excess of ten times the Weight of the acetylene is commonly advantageous from the standpoint of yield, and even twenty or more times is sometimes preferred. 7

The catalysts used are the cobalt carbonyls and the compounds formed by reaction of cobalt carbonyl with electron donor solvents such as ketones and nitriles that' The dilactones of this invention are useful as inhibitors for light catalyzed polymerizations, as shown below:

One percent by weight of the dilactone of Example I was added to freshly distilled monomeric methyl methacrylate under nitrogen andthe mixture sealed in a tube.

The mixture was then irradiated with two black light fluorescent lamps (General Electric) at a distance of 3.5 inches for 7.5 hours. At the end of this time there was no noticeable increase in the viscosity of the methyl methacrylate, indicating that no polymerization had occurred.

Monomeric methyl methacrylate, without added dilactone, irradiatedunder the same conditions and for the same length of time, was converted to a very thick syrup.

The dilactone of Example IV exhausts readily into Dacron polyester fiber, acetate, and Orlon acrylic fiber, giving yellow to orange dyeings of good stability to laundering. This is illustrated below: i 7

Three solutions of 0.015 g. of the dilactone of Example I IV in 5 ml. of methyl Cellosolve were prepared. Each,

solution was then diluted with 40 ml. of boiling water containing 0.2 ml. of acetic acid. Skeins of Dacron polyester fiber, Or1on acrylic fiber, and cellulose acetate were immersed in each solution and permitted to simmer for one hour. In all three cases good dyeings of the fibers with exhaustion of the dye bath occurred. After dyeing the fibers were rinsed in running water for 5 minutes, then boiled in 1% soap solutions for 5 minutes, followed by soaking in running water for 30 minutes. In all cases permanent dyeings were obtained;

The dilactones of this invention can be hydrogenated in acetic acid with a platinum catalyst to obtain sube'ric acids, which are useful for the preparation of fiber-formingpolyesters. In addition to acetic acid, other organic solvents can be used, such as dioxane, ethyl acetate, tetrahydrofuran and dimethylformamide.

The unsaturated dilactones of this invention can be ladium catalyst to the corresponding hexahydrodilactones '15 of the formula C (RR) H O which can be represented by the general structural formula H H |3- I H wherein one free valence of each ring is satisfied by R and the other free valences of said rings are satisfied by R, said R and R being defined as aforesaid with respect to the unsaturated dilactones. In a preferred method for effecting the hydrogenation, the reaction is eifected with 10% palladium-on-carbon at room temperature (ca 20 C.) and 45 lb./sq. in. pressure using dioxane or acetic acid as the reaction medium. The hexahydrodilactones can be used as modifiers for polymeric resins such as a plasticizer for vinyl chloride resins.

The products of this invention are useful as fungicides. This is illustrated by the results of greenhouse tests with tomato plants as described by McCallan and Wellrnan (Crop Protection Digest, bulletin 68, July 1943, pages 93-134). In such as test one set of tomato plants is sprayed with a 0.0016% aqueous solution of the dilactone of Examples I and II and another set with a 0.2% aqueous solution of the same dilactone. The treated plants, along with a corresponding group of untreated controls, are incclulated with tomato early blight A'lternarz'a solani). When the control plants showed 100% disease, the plants treated with the 0.2% solution of dilactone showed 2% disease and those with the 0.0016% dilactone solution 24% disease.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A dilactone having the structural formula wherein R and R are selected from the class consisting of hydrogen, alkoxyaryl where the alkoxy radical is not more than 12 carbon atoms and the aryl radical is hydrocarbon of not more than 10 carbon atoms, haloaryl where the aryl radical is hydrocarbon of not more than 10 carbon atoms, and monovalent hydrocarbon radicals, free from non-aromatic unsaturation, of not more than 12 carbon atoms, said dilactone giving a suberic acid on hydrogenation with a platinum catalyst in acetic acid.

2. A dilactone having the structural formula wherein R and R are selected from the class consisting of hydrogen, alkoxyaryl where the alkoxy radical is not more than 12 carbon atoms and the aryl radical is hydrocarbon of not more than 10 carbon atoms, haloaryl where the aryl radical is hydrocarbon of not more than 10 carbon atoms, and monovalent hydrocarbon radicals, free from non-aromatic unsaturation, of not more than l2 carbon atoms, said dilactone giving a suberic acid on hydrogenation with a platinum catalyst in acetic acid.

3. [A -bifuranl-5,5dione.

4. The trans form of [A -bifuran]-5,5-dione having the structural formula 5. The cis form of [A -bifuran]-5,5'-dione having the structural formula 0 0 O=O/ \G=C/ c=o m (311 Elk-(5H 6. Process for preparing a dilactone which comprises reacting an acetylenic compound in an inert organic liquid reaction medium free from active hydrogen, with carbon monoxide under a pressure of at least 50 atmospheres, at a temperature within the range of 60 to C., and in contact with a cobalt carbonyl catalyst, said acetylenic compound corresponding to the formula R.CECR' wherein R and R are selected fromrthe class consisting of hydrogen, alkoxyaryl where the alkoxy radical is not more than 12 carbon atoms and the aryl radical is hydrocarbon of not more than 10 carbon atoms, haloaryl where the aryl radical is hydrocarbon of not more than 10 carbon atoms, and monovalent hydrocarbon radicals, free from non-aromatic unsaturation, of not more than 12 carbon atoms, and obtaining as the resulting product a dilactone as defined in claim 11.

7. Process for preparing a dilactone as set forth in claim 6 wherein the carbon monoxide is present in said reaction medium in proportion of at least two moles per mole of acetylenic compound.

8. Process for preparing a dilactone which comprises reacting acetylene, in an inert organic liquid'reaction medium free from active hydrogen, with carbon monoxide under a pressure of at least 50 atmospheres, at a temperature within the range of 60 to 175 C., and in contact with a cobalt carbonyl catalyst, and obtaining as the resulting product [A fi -bifuran]-5,5'-dione.

9. Process for preparing a hexahydrodilactone which comprises hydrogenating a dilactone of claim 11 in contact with a palladium catalyst, and obtaining as the resulting product a hexahydrodilactone of the formula C (RR) H O wherein R and R are defined as in said claim 11. V

10. Process for preparing a hexahydrodilactone which comprises hydrogenating [A -bifuran]-5,5'-dione in contact with a palladium catalyst, and obtaining as the resulting product the hexahydrodilactone of [A bifuran]-5,5-dione.

11. A dilactone having one of the structural formulas and wherein one free valence of each ring is satisfied by R and the other free valence of each ring is satisfied by R, said R and R being selected from the class consisting of hydrogen, alkoxyaryl where the alkoxy radical is not more than 12 carbon atoms and the aryl radical is hydrocarbon of not more than 10 carbon atoms, haloaryl where the aryl radical is hydrocarbon of not more than 10 carbon atoms, and monovalent hydrocarbon radicals, free from non-aromatic unsaturation, of not more than 12 carbon atoms, said dilactone giving a suberic acid on hydrogenation with a platinum catalyst in acetic acid.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Loder et a1 Aug. 11, 1942 Hopff Nov. 17, 1942 Fang June 2, 1953 Logan Dec. 15, 1953 Urban Sept. 7, 1954 18 OTHER REFERENCES Fang et al.: J. Org. Chem. 16, 1231-7 (1951).

Chem. Abst. 46, page 1794d (1952). 

11. A DILACTONE HAVING ONE OF THE STRUCTURAL FORMULAS 